A candidate backed by Prime Minister Shinzo Abe has won an election for governor of Tokyo after the previous city head resigned last year amid scandal.

The victory of former health minister Yoichi Masuzoe was widely expected.

Masuzoe, 65, won by a wide margin, according to media exit polls.

Voters chose Masuzoe from a field of 16 to lead the city of 13 million people. He will be tasked with such things as starting preparations for the 2020 Olympics, preparing for a long-feared huge earthquake and deciding whether to end Japan's nuclear dependency.